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Abstract

Effects of salinity, temperature and phosphorus concentration on the chemical composition of Gelidium crinale (Turner) Lamouroux (Gelidiaceae, Rhodophyta). The effects of different culture conditions (temperature, salinity and dissolved inorganic phosphorus) were investigated for seven days, under controlled conditions. The maximum production of proteins occurred in cultures where the temperature was 25°C, with concentrations of 5.0 and 10.0 ?M of dissolved inorganic phosphorus and salinity between 15 and 20 psu, with values varying from 2.62 to 2.83% of algae dry weight. For carbohydrates, a third-order interaction was not observed in the statistical analysis; only a second order interaction was observed between temperature and inorganic phosphorus concentrations (P < 0.005) and between temperature and salinity (P < 0.000). The greatest phosphorus increase in the thalli (0.80 %) occurred in the lowest temperature (15 °C), associated with low salinity (10 psu) and high inorganic phosphorus concentration (10.0 ?M). The Pearson’s correlation coefficient revealed positive correlations (P < 0.001) among protein content, temperature and inorganic phosphorus available in the growth medium. For carbohydrates, correlations were positive with all three abiotic parameters. For tissue phosphorus, a positive correlation occurred only with dissolved inorganic phosphorus; with temperature and salinity,
the correlations were negative. Among the chemical components present in the algae, proteins and carbohydrates showed a positive correlation, while tissue phosphorus presented a negative correlation with both, although this correlation was not significant with regard to protein.